Disposable, plastic inoculation loops for culturing microorganisms are known in the art. These are often formed of moldable synthetic resins, such as polystyrene or polypropylene. These inoculation loops are generally shaped as a rod having a loop eye formed on one of the rod's ends and are used for streaking culture media employed in culturing microbes. Culturing may be carried out using any of many different types of bodily fluids. These include, but are not limited to, urine, blood, saliva, etc.
When culturing a sample of a bodily fluid, the volume of fluid transferred from the sample collection vessel to the culture medium (or media) must be known with reasonable accuracy. Accordingly, when using an inoculation loop, the end with the loop eye must be immersed in the fluid sample up to a pre-determined level. Generally, when dipping the loop eye into the liquid too far or not far enough, an incorrect volume of liquid is transferred to the culturing medium. The number of colony forming units (cfu) found in microbial cultures is a quantitative measure predicting infection. Since the cfu count is directly dependent on the volume of sample used, false positives and false negatives often result when incorrect volumes are used.
The whole culturing process must be kept free from contamination. Contamination can occur in the sample collection vessel itself since the vessel is usually uncovered for at least a short period of time. It may also occur during the transfer of sample to be cultured via the inoculation loop to a Petri dish filled with a culture medium. During the transfer, the inoculation device may be exposed to air-borne microorganisms, and the longer the exposure, the greater the likelihood of contamination. After using the inoculation loop to streak the culture medium with the sample, the medium is incubated for a prescribed period.
Normal culturing uses an inoculation loop to transfer a sample to be cultured from a sample collection vessel to a growth medium (media) in a Petri dish. Typical inoculation loops and their use are described in U.S. Pat. Nos. 4,892,831 to Wong; 4,687,746 to Rosenberg et al; and 5,279,964 to Chrisope, all of which are incorporated by reference herein.
Recently, other types of devices for microbial culturing of urine, e.g. the dipslides of Oxoid Ltd. of Basingstoke UK or Orion Diagnostica Oy of Espoo Finland, and the DipStreak of Novamed Ltd. of Jerusalem Israel, have been developed. These devices are plastic plates, each side of which is coated with a different culture medium. The dipslide is totally immersed in the bodily fluid. The DipStreak has projections which are carefully and partially immersed in the bodily fluid. The projections are then detached and used to streak both sides of the culture media coated plate. Both dipslides and the DipStreak devices still suffer from the disadvantages noted above. They are susceptible to sample contamination and quantitative analysis of the sample is susceptible to false readings. In addition, these devices are generally more costly then inoculation loops used in conjunction with culture medium filled Petri dishes. Sample contamination occurs inter alia because the collection vessel is typically an open vessel. Additionally, these devices are not stable and require two handed use, one hand holding the collection vessel and the other holding the dipslide or DipStreak.
In view of the above, it would be advantageous to develop an inoculation system for bacteriological or microbial culturing of bodily fluids which reduces the dangers of contamination. Additionally, it would be advantageous to develop a system wherein the culturing of microbes in body fluids would not require extremely careful immersion of an inoculation loop in the fluid sample. With less care required, persons not necessarily trained in microbiological procedures can use the system. There is a need for an inoculation system which will reduce the false positive and false negative results when culturing microbes. It would also be advantageous to develop a system that is disposable and of low cost.